Asirvatham, Samuel

Introduction: The predictive value of left atrial (LA) volume and reservoir function (ResF) post-atrial fibrillation (AF) ablation has been scarcely studied. Hypothesis: Abnormal LA volume and ResF post-ablation are associated with adverse cardiovascular events. Methods: We analyzed LA maximum (LAVImax) and minimum (LAVImin) volume index, and 2 measures of ResF, emptying fraction (LAEF) and expansion index (LAEI), prospectively measured at 3-month post-procedure in patients in sinus rhythm who underwent AF ablation between 2007-2016. Composite endpoint (CE) at follow up was all-cause mortality, cardiac hospitalization (heart failure or acute ischemic event) and stroke. Results: 792 patients were studied ( age 60±10 years, 25% women ; Table 1) . Over 7.5 years [IQR 3.0-9.7], 96 (12%) patients experienced CE, which was more prevalent in patients with enlarged LA and reduced ResF. Impaired LA volumes and ResF were each independently associated with CE ( Fig.1 ), even after adjustment for clinical, demographic and echo characteristics (Model A, Fig.2 ) (LAVImax ≥35 ml/m 2 : HR 2.15 [95% CI, 1.35-3.43], p=0.001; LAVImin≥20.5 ml/m 2 : HR 2.88 [1.77-4.69], p<0.0001; LAEF<39%: HR 2.00 [1.31-3.05], p=0.001; LAEI<65%: HR 1.95 [1.27-3.01], p=0.003). ResF measures (LAEF and LAEI) were incremental to LAVImax (all p<0.05), but not LAVImin (all p>0.05; Fig.2 ). In patients with normal LA (LAVImax <35 ml/m 2 ; n=408), increased LAVImin (≥20.5 ml/m 2 ) remained associated with CE (HR 3.11 [1.45-6.67], p=0.004) and cardiac hospitalization (HR 5.81 [1.87-18.01], p=0.002). These findings were independent of AF recurrence. Conclusions: In these patients, enlarged LA and impaired ResF at 3-month post-ablation were strongly associated with adverse cardiovascular outcomes, regardless of AF recurrence. Measures of LA ResF were incremental to LAVImax. Notably, LAVImin showed the strongest associations and even identified a high-risk subgroup among patients with non-dilated LA.

Introduction: Carcinoid heart disease (CHD) is a rare sequelae of hormonally active neuroendocrine tumors that often requires cardiac surgical intervention. Little is reported on cardiac implantable electronic device (CIED) implantation in the CHD patient population. Hypothesis: We sought to establish the safety and efficacy of CIED implantation in patients with CHD. Methods: We retrospectively reviewed patients with a diagnosis of CHD who underwent CIED implantation at our institution (Mayo Clinic) and evaluated indications for implant, perioperative complications, and mortality. Results: A total of 27 patients with a cumulative follow up of 75 patient-years were identified during the study period. The most common indication for device implant was high grade atrioventricular block (n=18, 66.7%). 14 (51.8%) had baseline conduction disease and 26 (96.2%) underwent cardiac surgery prior to CIED implant. The majority of devices implanted were dual chamber permanent pacemakers (PPM) (n=17, 63.0%), while other devices included single chamber PPM, epicardial PPM, chronic resynchronization devices, and intracardiac defibrillators. Peri-operative complication occurred in 6 patients (22.2%), with 2 patients requiring ICU level care. No patient suffered carcinoid crisis during implantation and there was no peri-implant mortality. Long term, 3 patients required device extraction: 1 for infection, 1 for lead related pain, and 1 for generator migration. The median time to death from implant was 2.5 years, with one-year mortality at 15%. Conclusions: In this unique cohort of patients with CHD, CIED can be performed safely. CIED most often occurred in the post cardiac surgical period and carcinoid crisis was uncommon.

BACKGROUND. Nearly half of strokes in non-valvular atrial fibrillation (NVAF) are due to non-cardioembolic mechanisms including carotid disease, lacune, watershed, venous sinus thrombosis, or hemorrhage. Tools capable of identifying those AF patients most likely to suffer a cardioembolic complication of AF would be very helpful for deciding which patients to treat with anticoagulants compared to aspirin. CHA 2 DS 2 -VASc has been advocated as an improved stroke risk assessment tool for NVAF patients. METHODS. CHA 2 DS 2 -VASc was compared to CHADS 2 for the prediction of left atrial appendage thrombus (LAAT), and association (Spearman correlation) with spontaneous echo contrast (SEC), left atrium appendage emptying velocity (LAAEV), left atrium volume index (LAVI) in consecutive NVAF patients undergoing echocardiographic study (10/1/2007 - 9/30/2009). RESULTS. 525 NVAF patients (age 62±13 years; 25% women; 28% persistent AF and 17% permanent AF) were parsed by extent of atrial blood stasis/LAAT ( Table ). CHA 2 DS 2 -VASc and CHADS 2 were similar for the prediction of LAAT (Figure). Measures of SEC intensity (0.416 vs 0.414;), LAAEV (-0.393 vs -0.344), and LAVI (0.322 vs 0.303) carried similarly associations with CHA 2 DS 2 -VASc and CHADS 2 scores. CONCLUSION. The challenge of stroke prevention in NVAF is balancing the risk and benefit of anticoagulant therapy. CHA 2 DS 2 -VASc does not improve the identification of patients with LAAT or low atrial mechanical function compared to CHADS 2 . Moreover CHA 2 DS 2 -VASc appears to overestimate the score of low risk patients for whom antiplatelet therapy would be sufficient and is more cumbersome compared to the original CHADS 2 .

Background: Whether a significant proportion of cryptogenic stroke (CS) is caused by under-detected paroxysmal atrial fibrillation (PAF) is not known. Prolonged ambulatory cardiac monitoring may detect episodes of PAF in patients with stroke of unknown cause (cryptogenic stroke, CS). However, it is unclear whether PAF is more common in patients wtih CS compared with patients with stroke of known cause (SKC). We performed a case control study to compare the rates of detection of PAF in CS vs SKC using prolonged ambulatory cardiac rhythm monitoring. Methods and Results: We prospectively enrolled 132 patients within 3 months of a stroke (66 with CS and 66 with SKC) to undergo 3-week ambulatory cardiac rhythm monitoring using the CardioNet MCOT system. Stroke group was assigned by consensus between two vascular neurologists upon enrollment based on the Causative Classification of Stroke system. Primary endpoint was detection of PAF of any duration independently confirmed by two cardiologists blinded to the stroke group. The groups were well balanced except that patients with CS tended to be older and to have less hypertension and diabetes. Four patients (2 in each group) were excluded because of insufficient stroke evaluation or early discontinuation of monitoring. Episodes of PAF were detected in 16/64 (25%) patients with CS and 9/64 (14%) patients with SKC (p=0.12). Only 5 patients had episodes of PAF lasting > 30 seconds (3 with CS and 2 with SKC). Six of the 9 patients from the SKC group with PAF had small subcortical infarctions; the other 3 had cortical strokes ascribed to artery-to-artery embolism (2 with complex aortic plaques, 1 with severe vertebrobasilar stenosis). In patients under age 65, episodes of PAF were more common in the CS group (22% vs 3; p=0.07) while in patients age 65 or older the rates of detection were very similar (29% in CS vs 28% in SKC; p=0.9). Conclusions: Very short episodes of PAF are relatively common in patients with CS and with SKC, and their pathogenic significance is unclear. However, considering only patients under 65, a greater proportion of cryptogenic stroke patients had PAF, suggesting it might be pathogenic.

Background: Transcatheter aortic valve replacement (TAVR) is often complicated by AV block requiring pacing, but whether patients recover AV conduction and whether the need for pacing affects outcomes is unknown. Methods: We retrospectively studied 534 patients who underwent TAVR at Mayo Clinic in Rochester, Minnesota between November 2008 and January 2015. Of these, 115 patients had implantable cardiac devices. Data was collected from subsequent device follow-ups to determine pacemaker dependency and percentage pacing. Results: 44 patients (8.2%) had devices implanted in the immediate post procedural period. The most common indications for implantation were high grade AV block (18 patients) and complete heart block (14 patients). 17/44 (38.6%) patients were pacemaker-dependent at implant and only 4 of these patients were no longer pacemaker-dependent during subsequent followup. The indication for pacing among these four patients was high grade atrio-ventricular block (2 patients), asystole (1 patient) and complete heart block (1). Among non-pacemaker-dependent patients, no significant change in the ventricular pacing percentages was noted over time. Survival was similar between patients who required device implantation post TAVR and those who did not after adjustment for age and gender (HR 0.73 [0.39-1.36], p=ns; figure) Conclusion: Patients requiring pacing after TAVR are often pacemaker-dependent at the time of implant. It is uncommon for patients who are dependent at the time of implant to regain AV conduction, but the need for cardiac pacing is not associated with increased mortality.

Introduction: Highly precise irradiation using carbon-12 (12C) ions is a new means for catheter-free ablation. Besides energy deposition leading to the dose distribution, nuclear interactions lead to by-product β+-activity that can be measured using positron-emission-tomography (PET). Hypothesis: In-beam PET scanning during focused myocardial irradiation using 12C can adequately depict 12C dose deposition. Methods: Pigs were irradiated with 25, 40, and 55 Gy for AV node (AVN), LA-PV junction, and local LV freewall ablations. PET measurement was performed by means of a double head camera system installed at irradiation site. Coincidences were captured in end-expiration during beam extraction pauses of the accelerator. Results: Evaluation of PET images was qualitatively performed using the coronal plane of the activity distribution superimposed on the contrast-CT in the center of the target contour. Strong β+-activities were measured in AVN and LV ablations. In AVN ablations, activity was localized to the target location, without target activity spreading to the level of the aortic root or coronary sinus (Figure A). Local LV irradiations revealed strong activity in the target location, slightly extending into left lung and chest wall (Figure B). In 55 Gy animals, the cardiac entry channel showed increased activity, decreasing in 40 Gy and more so in 25 Gy animals. Conclusion: This is the first study applying in-beam PET to track 12C dose-deposition into the target location for catheter-free ablation in intact animals. Correlation of β+-activity to electrophysiological outcome, lesion induction, and potential side-effects may be critically important in dosing therapy and predicting outcomes.

Background: Worldwide, approximately one million patients have had total hip arthroplasty with 35% being cobalt and chromium Metal-on-Metal (MoM) or Metal-on-Polythelene (MoP) implants. Animal models have suggested that cobalt and chromium can affect all chambers, but there seems to be an atrial predilection. There are several case reports of metal containing hip arthroplasty causing atrial arrhythmias but the true incidence of atrial fibrillation associated with metal hip arthroplasty remains undefined. Objective: We sought to determine the incidence of atrial fibrillation in patients with metal containing hip arthroplasty. We also examined the association between serum cobalt and chromium levels and arrhythmias in this cohort and all cause mortality. Methods: We retrospectively examined the records of patients from the Mayo Clinic total hip arthroplasty registry (Metal group - Metal-on-Metal: MoM and Metal-on-Polyethylene: MoP, Non-Metal group - Ceramic-on-Ceramic: CoC and Ceramic-on-Polyethylne: CoP) to obtain demographic data, comorbidities, laboratory, ECG, and echocardiographic data. Out of a total of 1756 patients, Cobalt and Chromium levels were available in 138 patients. Results: The mean age of patients with metal containing hip replacement was 50 years and were predominantly male. During a follow up period of 10 years, the incidence of atrial fibrillation in our study population was 8% in metal group compared to 2% (p=0.11) in non-metal group. There was no association between cobalt or chromium levels with the incidence of atrial fibrillation. All-cause mortality was significantly higher in metal group versus non-metal group (p=0.005). Conclusion: The incidence of atrial fibrillation was relatively more in patients with metal versus non-metal hip arthroplasty but there was no association of serum cobalt or chromium levels with incidence of atrial fibrillation in the subset of patients. In addition, all-cause mortality was significantly higher in the metal group suggesting potential toxic effects of metal containing hip arthroplasty.